1. Field of the Invention
The present invention relates to the field of stoves, furnaces and the like which have flues vented through a wall, and more particularly to an apparatus for providing insulation of the wall against the heat in such vents.
2. Background of the Invention
Various types of stoves, furnaces and the like include vent pipes for exhausting combustion products through a wall or ceiling to the outside of a building. Since the vent pipes can become quite hot, it is necessary to insulate the wall or ceiling against such heat. This is particularly true in the case of wood frame buildings which could become damages, or catch fire, as a result of exposure to this considerable heat.
It is presently common to employ a structure known as a flue thimble to connect the vent pipe on the interior of a building with the exterior chimney. A flue thimble typically comprises a cylindrical piece of formed masonry which extends from a point flush with the inside of the dwelling wall to a point inside of the masonry flue lining of the chimney. The vent pipe is telescopingly received within the flue thimble, and in common applications the only insulation for the wall is the thimble itself.
Modified forms of the flue thimble have been proposed in the prior art. In U.S. Pat. No. 1,160,954, issued to Parker on Nov. 16, 1915, there is described a heating stove which utilizes a specialized form of a flue thimble. The Parker patent discloses a vertical venting pipe which is separate from the stove and is positioned adjacent the exterior wall. The top end of the vertical pipe connects with a horizontal pipe that extends through the exterior wall and is open at the outside end. The vent pipe coming from the stove extends into and through the horizontal pipe to a location about in the center of the exterior wall. Air is thereby permitted to move upwardly through the horizontal pipe and around the vent pipe of the stove, at which point it combines with the exhaust air of the stove and passes to the outside of the building. Since the air from the vertical pipe passes around the vent pipe of the stove, a degree of dilution of the exhaust air of the stove is accomplished, thus reducing the temperature to which the exterior wall is exposed.
Another modified flue thimble is described in U.S. Pat. No. 386,166, issued to Schaab on July 17, 1888. The Schaab device actually utilizes a plurality of flue thimbles which are concentrically received within one another to accomodate vent pipes of different sizes. Each smaller thimble is secured to the adjacent, outer one, and is removable therefrom in the event that the size of the vent pipe requires a larger opening. A relatively simple flue thimble is described in U.S. Pat. No. 2,464,084, issued to Helt on Mar. 8, 1949. The Helt device includes a rectangular conduit mounted within the exterior wall, and two plate halves which are mounted from opposited sides of the vent pipe to engage the pipe and cover the surrounding area of the rectangular conduit.
Other variations of the flue thimble have also been described. Examples of other types of modified forms are contained in U.S. Pat. Nos. 2,687,127, issued to Leffler on Aug. 24, 1954; 922,714, issued to Meredith on May 25, 1909; 843,797, issued to Dauben et al. on Feb. 12, 1907; and 458,416, issued to Devore on Aug. 25, 1891.